A device of this type for the laser welding of a workpiece is used for example for the production of moulds for plastics material parts. For example, modern aeroplanes are increasingly manufactured from fiber-reinforced plastics materials. In this case, in comparison with other plastics material components, the components often have very large dimensions, in the range of up to 40 m in length.
However, in comparison with similarly large plastics material components from the field of yacht construction or large containers, there are significantly higher quality requirements for the components. The high quality standards are reflected in the very complex configuration of the moulds which are used for the production of the components. These are subject to a number of constraints:
High form and dimensional stability
Long endurance under cyclical thermal stress in the autoclave
Thermal expansion suited to the plastics material
Low weight
Helium-tightness of the mould surface.
These main requirements are met by a suitable selection of material—in many cases steels with a high proportion of nickel are used—and by an optimized design. The substructure of the actual mould surface is produced from a three-dimensional lightweight sheet metal structure. The actual mould surface on which the fiber-reinforced plastics material component is constructed is then applied to this substructure. The size of the moulds presents the manufacturing companies with serious difficulties, because worldwide, only a few machines are capable of working on workpieces longer than 10 m in one clamp. The dimensions also result in a transport problem. The transport costs escalate as the size increases.
The possibility of segmenting the large moulds, in order to produce individual modules with maximum dimensions suited to the manufacturing capacity of average plants and then to join then by a joining operation at the location where the mould is to be used, has also already been considered. In this case, the joining operation has to meet two basic requirements. On the one hand, the joining operation requires low-heat joining in order to minimize distortions. On the other hand, the gas-tightness of the joined mould must be ensured.